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Biomedical subjects

W C Oliver

Publications and source records attributed to W C Oliver.

18 recordsLinked to original sources
PubMed1996

The predictors of red cell transfusions in total hip arthroplasties.

BACKGROUND: Most blood crossmatched in a hospital blood bank is for surgical patients, and the majority is never transfused. The maximal standard blood order schedule is used to promote efficient ordering practices for surgical patients. STUDY DESIGN AND METHODS: To ascertain the predictors of red cell transfusions for patients undergoing total hip arthroplasty, the charts of 299 adult patients undergoing primary and revision total hip arthroplasty were reviewed. A surgical blood order equation was developed for calculating the number of units of red cells that should be ordered. Stepwise regression analysis was used to determine which patient-and-case-related variables should be considered in the surgical blood order equation. RESULTS: The significant indicators for allogeneic red cell transfusion to patients on the day of total hip arthroplasty were preoperative hemoglobin concentration, weight, age, estimated blood loss, and aspirin use. The surgical blood order equation would result in a lower crossmatch-to-transfusion ratio than would the maximal standard blood order schedule (1.23 vs. 3.14). Costs were also lower with the surgical blood order equation. CONCLUSION: Incorporation of patient factors resulted in increased efficiency of blood-ordering practices in total hip arthroplasty.

Adult↗
PubMed1996

The relationship between cerebral blood flow and transcranial Doppler blood flow velocity during hypothermic cardiopulmonary bypass in adults.

A noninvasive, simple, and continuous method to assess cerebral perfusion during cardiopulmonary bypass (CPB) could help prevent cerebral ischemia. Transcranial Doppler sonography (TCD) allows a noninvasive, on-line measurement of blood flow velocity in cerebral arteries. The correlation of TCD-estimated and actual cerebral blood flow (CBF) has not been well studied during CPB. We determined the correlation of middle cerebral artery (MCA) mean velocity and CBF determined by the Kety-Schmidt method during nonbypass and two hypothermic bypass flow conditions. Sixteen patients undergoing hypothermic (27 degrees C) CPB for coronary artery bypass grafting and/or valve replacement surgery were enrolled in the study. We were able to determine MCA velocity in only 12 patients. We determined CBF and MCA velocity in each patient during four 15-min study periods: 1) prebypass after sternotomy before aortic cannulation; 2) hypothermic (27 degrees C) CPB with 1.2 L.min-1.m-2 pump flow; 3) hypothermic CPB with 2.4 L.min-1.m-2 pump flow, and 4) 30 min after weaning from CPB. There was no difference in the mean arterial pressure between the two CPB pump blood flows. The pooled change in MCA velocity and CBF as percentage of baseline (prebypass) for all patients and at all time points had a correlation of 0.33 (r). A decrease or increase in MCA velocity did not necessarily indicate a corresponding decrease or increase in CBF. This technology may be of limited usefulness during the circulatory condition of hypothermic, nonpulsatile CPB.

Aged↗
PubMed1995

Cerebral blood flow during cardiac operations: comparison of Kety-Schmidt and xenon-133 clearance methods.

This study simultaneously compared the standard Kety-Schmidt and the modified xenon-133 (133Xe) clearance techniques for measuring cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) during cardiac operations. The validity of the CBF method is important because our management of the patient during cardiopulmonary bypass (CPB) is based, in part, on our understanding of the cerebral hemodynamics during CPB. In 20 patients undergoing coronary artery bypass grafting, CBF and CMRO2 were determined by both methods. Measurements were made before onset of CPB and once during CPB. Ten patients underwent CPB with systemic normothermia (37 degrees C) and 10 with systemic hypothermia (27 degrees C). Anesthesia consisted of fentanyl and midazolam. CPB pump flows were kept at 2.2 to 2.4 L.min-1.m-2 and alpha-stat pH management was used. Xenon-133 clearance significantly underestimated CBF and CMRO2 relative to the Kety-Schmidt technique before CPB and at both bypass temperatures. Values obtained by 133Xe clearance were approximately 50% of that measured by the Kety-Schmidt method. The modified 133Xe technique as typically used during cardiac operations does not appear to measure CBF accurately; this leads to corresponding errors in CMRO2 calculations. Determination of CMRO2 and cerebral autoregulatory function during cardiac operations appears to be more appropriate if based on the more direct Kety-Schmidt technique. Accordingly, our management of CPB with respect to cerebral perfusion as it has been determined by the modified 133Xe clearance method may require reassessment.

Blood Gas Analysis↗
PubMed1995

Determination of normal versus abnormal activated partial thromboplastin time and prothrombin time after cardiopulmonary bypass.

OBJECTIVE: The study's objective was to determine the prothrombin time (PT) and activated partial thromboplastin time (aPTT) values that differentiated normal from excessively bleeding patients immediately after cardiopulmonary bypass (CPB). DESIGN: A prospective blinded study. SETTING: A large academic medical center. PARTICIPANTS: 148 patients were studied. INTERVENTIONS: aPTT and PT were determined by the hospital laboratory and the Biotrack 512 Coagulation Monitor (Ciba Corning Diagnostics, Medfield, MA) from an arterial whole blood sample obtained 10 minutes after protamine administration. Patients were subjectively and objectively defined as "bleeders" or "nonbleeders" with blinded observers. MEASUREMENTS AND MAIN RESULTS: The specificity and sensitivity were determined by a receiver operating characteristic (ROC) analysis. Twenty-three of 148 patients (14.9%) were characterized as bleeders. The laboratory PT had a maximal specificity and sensitivity of 78% and 75%, respectively, at a value of 15.4 s, with a negative and positive predictive value of 93% and 33%, respectively. The maximal specificity and sensitivity of the laboratory aPTT was 64% and 76%, respectively, at a value of 46 s, with a negative and positive predictive value of 89% and 33%, respectively. aPTT and PT approached normal values after 12 hours in the intensive care unit. CONCLUSION: The aPTT and PT values that produce the maximal sensitivity and specificity in the ROC analysis may be helpful to differentiate patients who are bleeding excessively from those patients who are not after CPB and to guide transfusion of blood products. New whole blood coagulation devices with rapid turn-around times had similar predictive value for bleeding tendency compared with standardized laboratory tests.

Adult↗
PubMed1994

Perioperative interventions to decrease transfusion of allogeneic blood products.

OBJECTIVE: To discuss some of the many options available for decreasing perioperative transfusion of allogeneic blood products. DESIGN: We review the issues that focus on the goal of developing an appropriate transfusion strategy in consideration of the individual patient's preexisting conditions, physiologic requirements, perioperative stress, and coagulation status. RESULTS: Increased awareness of transfusion-related morbidity from allogeneic blood products has resulted in increased development and application of alternatives to allogeneic transfusion. Preoperative donation and perioperative collection of autologous blood and blood products decrease exposure to allogeneic blood. Pharmacologic agents, such as antifibrinolytics, may also decrease the need for allogeneic transfusion. Perioperative use of laboratory tests of coagulation function facilitates the rapid and specific diagnosis of coagulation disorders. CONCLUSION: Physicians now have considerable appreciation of the risks and benefits of blood product transfusion. This knowledge has resulted in conservative and scientific approaches to therapy for perioperative bleeding and coagulopathy.

Blood Coagulation Disorders↗
PubMed1994

A prospective, randomized comparison of cerebral venous oxygen saturation during normothermic and hypothermic cardiopulmonary bypass.

Recent reports have described cerebral venous oxygen desaturation during and after rewarming from hypothermic cardiopulmonary bypass. Additionally, patients undergoing normothermic cardiopulmonary bypass may be at higher risk for neurologic injury. This study was designed to determine whether patients undergoing normothermic cardiopulmonary bypass are at increased risk for sustained cerebral desaturation. Fifty-two patients undergoing first-time coronary artery bypass grafting were randomized to receive normothermic (37 degrees C, n = 26) or hypothermic (27 degrees C, n = 26) cardiopulmonary bypass. The anesthetic was standardized and alpha-stat pH management was used. A 4F oximetric catheter was placed in the jugular bulb and cerebral venous and radial arterial blood were sampled. Oxygen partial pressure and saturation were measured at six intervals from cerebral venous blood and from radial arterial blood. Patients receiving normothermic cardiopulmonary bypass had lesser values of oxygen partial pressure and saturation in cerebral venous blood than patients subjected to hypothermia during the first 40 minutes of bypass. Cerebral venous desaturation (oxygen saturation in cerebral venous blood of 50% or less) was observed in 54% of patients in the normothermic group and 12% of patients in the hypothermic group during cardiopulmonary bypass. In the normothermic group, cerebral desaturation occurred primarily in early bypass (14 of 26). The three episodes of desaturation in the hypothermic group occurred during rewarming. During cardiopulmonary bypass, the arteriovenous oxygen content difference was greater in the normothermic group than in that in the hypothermic group, suggesting higher oxygen consumption. Differences in glucose utilization during early cardiopulmonary bypass between the groups was also detected. One patient in the hypothermic group had an embolic stroke and subsequently died. There were no other perioperative strokes or deaths in the study population. The present study demonstrates that patients undergoing normothermic cardiopulmonary bypass are at greater risk for cerebral desaturation. Because it is a global assessment, cerebral venous oxygen saturation may be insensitive to focal ischemic events. It remains to be seen whether these differences in cerebral physiologic states translate into differences in clinical outcome.

Aged↗
PubMed1993

Effects of cerebrospinal fluid drainage in patients undergoing thoracic and thoracoabdominal aortic surgery.

Cerebrospinal fluid (CSF) drainage has been reported to protect the spinal cord during surgical procedures requiring thoracic aortic cross-clamping. In 1986, CSF pressure monitoring and drainage was begun in an attempt to reduce the incidence of paraplegia associated with surgical repair of descending thoracic and thoracoabdominal aortic aneurysms (TAAA). These Group II patients (n = 50) were retrospectively compared to Group I patients (n = 49) who had undergone similar surgical procedures in the previous 3 years before CSF monitoring was introduced into this practice. Group II patients had intrathecal catheters placed for monitoring of CSF pressure and drainage of CSF to maintain the pressure < or = 15 mmHg. Seven patients (four in Group I, three in Group II) died before recovering from the anesthetic. Of the 47 patients in Group II who survived, none had clinically apparent complications such as an epidural hematoma or meningitis from the intrathecal catheter. The mean aortic cross-clamp time was 58.6 +/- 30.5 minutes (mean +/- SD) in Group I versus 65 +/- 42.6 minutes in Group II. Twenty-three patients in Group I and 16 patients in Group II had a shunt to the distal aorta. To maintain a CSF pressure of < or = 15 mmHg in Group II, an average of 46.9 +/- 6.9 mL of CSF was withdrawn. Of the 45 survivors in Group I, 4 developed a spinal cord deficit; the number of patients with spinal cord deficit in Group II was 4 out of the 47 who survived.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Intraoperative measurement of activated partial thromboplastin time and prothrombin time by a portable laser photometer in patients following cardiopulmonary bypass.

Intraoperative capabilities to rapidly assess coagulation status following cardiopulmonary bypass (CPB) may be of benefit in providing optimal hemostasis and transfusion management, because CPB causes abnormalities in coagulation that may increase morbidity and mortality. The Ciba Corning 512 coagulation monitor (Ciba Corning, Medfield, MA) is a compact and portable device that rapidly determines the prothrombin time (PT) and activated partial thromboplastin time (APTT) in whole blood samples. One hundred patients requiring CPB had APTT and PT determined in whole blood specimens by the 512 coagulation monitor and in plasma specimens by the hospital laboratory from the same arterial blood sample obtained after protamine administration. Correlation coefficients of 0.95 and 0.77 were obtained for the paired APTT and PT tests, respectively (P < 0.01). A bias of 12.6 seconds and 0.77 seconds was determined for the APTT and PT, respectively. The 95% confidence intervals of the bias of the APTT and PT were 9.7 seconds to 15.5 seconds and 0.3 seconds to 1.16 seconds, respectively. The 512 coagulation monitor provided APTT and PT results in less than 3 minutes compared to approximately 45 minutes for the hospital laboratory. A reduction in accuracy was associated with the 512 coagulation monitor PT and APTT when different sampling sites were used. The 512 coagulation monitor accuracy was not affected by a variation of hemoglobin concentration or platelet count between 6 and 12 gm/dL and 15 to 300 x 10(9)/L, respectively. In conclusion, the 512 coagulation monitor provided a rapid APTT and PT result, but the APTT was less accurate. Speeding access to hospital laboratory results would be even more efficacious and accurate.

Adult↗
PubMed1993

Autologous platelet-rich plasma does not reduce transfusion of homologous blood products in patients undergoing repeat valvular surgery.

BACKGROUND: Patients undergoing cardiac surgery employing cardiopulmonary bypass frequently require transfusion of homologous blood products and, therefore, are exposed to the risk of transfusions. Autologous platelet-rich plasma administration may reduce homologous transfusion and attendant risks. METHODS: In a blinded, randomized fashion, patients undergoing repeat sternotomy and valvular surgery received either a sham product (n = 28) or autologous platelet-rich plasma (n = 28) at the conclusion of cardiopulmonary bypass. Perioperative blood loss, coagulation profiles, and transfusion requirements were compared between the two groups. RESULTS: In the first 24 h postoperatively, both the platelet-rich plasma and sham groups received a median of 10.5 units of homologous blood products. Total median perioperative homologous transfusion requirements were 13 and 11.5 units for the platelet-rich plasma and sham groups, respectively. There was no significant difference in intraoperative or postoperative bleeding between the groups. CONCLUSIONS: Autologous platelet-rich plasma did not reduce perioperative bleeding or transfusion requirements in repeat valvular surgery.

Aged↗
PubMed1992

Operative treatment of Ebstein's anomaly.

From April 1972 to February 12, 1991, 189 patients with Ebstein's anomaly underwent repair. Ages ranged from 11 months to 64 years (median 16 years, mean 19.1 years). In 58.2%, tricuspid valve reconstruction was possible, and in 36.5%, a prosthetic valve, usually a bioprosthesis, was inserted. In 5.3%, a modified Fontan or other procedure was performed. There were 12 hospital deaths (6.3%). All 28 patients who had accessory conduction pathways (Wolff-Parkinson-White syndrome) underwent successful ablation of the pathways as part of the operative treatment. Follow-up was obtained in 151 (85.3%) patients. Of those patients followed up more than 1 year after operation, 92.9% were in New York Heart Association class I or II. There were 10 late deaths: seven cardiac (four sudden), two noncardiac, and one of an unknown cause. Postoperative Doppler echocardiographic assessment showed the atrial septum was intact in all patients and tricuspid valve function was good to excellent in most patients. Four of the 110 patients (3.6%) who underwent valve reconstruction required reoperation 1.4 to 14.1 years later. Postoperative reduction in heart size was usual, atrial arrhythmias were reduced, and late postoperative exercise testing showed a significant improvement in performance: Maximal oxygen consumption increased from a mean of 47% of predicted value before the operation to a mean of 72% after the operation. Nine patients had a total of 12 successful pregnancies with deliveries of normal children.

Abnormalities, Multiple↗
PubMed1991

Anesthesia, cardiopulmonary bypass, and the pregnant patient.

For the perioperative management of pregnant patients with severe cardiac or aortic disease who require a cardiac surgical procedure and cardiopulmonary bypass, a close, cohesive, working relationship must exist among several medical and surgical specialties. For appropriate management, the well-being of both the mother and the fetus must be considered. The best interests of the mother and the fetus may not coincide, and optimal therapy for one may be inappropriate for the other. We present 10 cases of severe cardiac or aortic disease in pregnant women who required surgical intervention. Eight patients underwent cardiopulmonary bypass during pregnancy, and two patients had cesarean section performed immediately before cardiopulmonary bypass. We also discuss the pertinent pharmacologic aspects related to the perioperative period and the management of cardiopulmonary bypass for the pregnant patient.

Adolescent↗
PubMed1990

Right ventricular outflow construction for complex congenital cardiac malformations without cardiopulmonary bypass: management and outcome of 44 patients.

A review of surgical and anesthetic techniques used in 44 consecutive patients to establish continuity between the right ventricle and pulmonary circulation, without extracorporeal circulation, as a first-stage repair in a variety of selected complex congenital cardiac lesions with right ventricular outflow obstruction, is presented. The overall operative mortality rate was 9% (four deaths), but no deaths occurred in the last 24 patients. Eleven patients (27.5%) have subsequently undergone complete repair and one patient (2.5%) underwent a Fontan repair. The advantages, anesthetic concerns, complications, and outcome are discussed.

Abnormalities, Multiple↗
PubMed1990

A comparison of washed red blood cells versus packed red blood cells (AS-1) for cardiopulmonary bypass prime and their effects on blood glucose concentration in children.

The effects on blood glucose concentrations of packed red blood cells (AS-1) (group I) versus washed red blood cells (group II) for cardiopulmonary bypass prime were compared in 20 infants weighing less than 10 kg undergoing cardiac surgical procedures. All patients were anesthetized with N2O/O2/isoflurane/fentanyl and received lactated Ringer's solution prior to bypass. Blood glucose concentrations prior to bypass were 85 +/- 15 mg/dl (mean +/- SD) in group I and 81 +/- 14 mg/dl in group II. Blood glucose concentrations were 210 +/- 21 mg/dl versus 78 +/- 14 mg/dl (P less than 0.001) 10 min after initiation of bypass, 241 +/- 48 mg/dl versus 107 +/- 28 mg/dl (P less than 0.001) prior to separation from bypass, and 214 +/- 52 mg/dl versus 97 +/- 19 mg/dl (P less than 0.001) after protamine administration in group I and group II, respectively. The use of washed red blood cells for cardiopulmonary bypass priming solution in infants significantly attenuates the increase in blood glucose concentration otherwise observed during cardiopulmonary bypass.

Adenine↗
PubMed1988

Outcome following posterior fossa craniectomy in patients in the sitting or horizontal positions.

Controversy continues to surround the use of the sitting position for neurosurgical procedures. This retrospective review of 579 posterior fossa craniectomies performed over a 4-yr period from 1981 through 1984 examines outcome following these procedures performed with the patients in either the sitting (n = 333) or horizontal (supine, prone, lateral, park bench) (n = 246) position. Multiple preoperative, intraoperative, and postoperative variables were analyzed. Venous air embolism occurred significantly more often in patients in the sitting position (45% versus 12%). However, no morbidity or mortality was attributed to venous air embolism. The incidence of hypotension with positioning was not different by position (19% in the sitting patients and 24% in the horizontal patients). Average blood replacement was significantly lower in the sitting patients (359 ml versus 507 ml), and the incidence of transfusion of greater than two units of blood was significantly higher in the horizontal patients (13% versus 3%). Postoperative cranial nerve function was significantly better in patients in the sitting group as compared to those in the horizontal group. The incidence of perioperative cardiopulmonary complications was not different between groups. These outcome data suggest that there are potential advantages and disadvantages of both the sitting and horizontal positions without supporting a significantly increased morbidity or mortality associated with either position.

Brain Diseases↗